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124 Cards in this Set

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What is the most important historic risk factor for subsequent preterm delivery?

Previous preterm delivery (increases risk by 20%); multiple prior preterm deliveries further increase risk

What are the other risk factors for preterm delivery?

- Multiple gestation


- Genitourinary infections (BV, Trich, Chlamydia, Gonorrhea, UTI, Pyelonephritis, asx bacteriuria)


- Other infections (eg, pneumonia, periodontal infections)


- Short cervical length (<20-25 mm)


- Uterine contractions


- Race (especially non-Hispanic blacks)


- Inter-pregnancy interval <6 months


- Pre-pregnancy BMI <19


- Toxin exposure (pollution, ozone, tobacco smoking)

What can be used to decrease the likelihood of preterm delivery?

Progesterone

In which patients is progesterone indicated to reduce the likelihood of preterm delivery?

- Patients w/ hx of prior preterm delivery


- Patients with a short cervical length

What can be used to assess risk for preterm delivery in women presenting with preterm contractions?

- Cervical length on transvaginal U/S


- Fetal fibronectin (fFN)

What is the most important intervention to improve neonatal outcomes in women presenting with preterm labor?

Antenatal Corticosteroids

What can be used to delay preterm delivery in order to allow time to administer steroids or transfer to a facility with a neonatal intensive care unit?

Tocolytics

What is the definition of preterm delivery?

Delivery before 37 weeks gestation

What is the incidence of preterm delivery?

11.4%


- 40-45% are due to spontaneous preterm labor with intact membranes


- 25-30% are associated with PPROM


- 30-35% are due to delivery by labor induction of C/S for medical indications

Is the incidence of preterm labors increasing or decreasing?

Was increasing in rate from 1981-2006, since then it has gradually decreased each year (likely due to dropping teenage birth rate and declining rate of higher order multiples); also possibly 2/2 reduction in elective early term (37-38 week) deliveries; also due to interventions (vaginal progesterone, IM 17-alpha-hydroxyprogesterone caproate, and use of cerclage

What are the racial disparities for preterm labor?

- Non-Hispanic whites: ~10%


- Non-Hispanic blacks: ~17%


- Hispanics: 12%

What cervical length is used as a cutoff for short cervix?

20-25mm

How does smoking affect risk for preterm labor?

- Smoking increases risk of preterm delivery and small for gestational age infants


- Dose dependent relationship (more smoking = more risk)


- Women who quit smoking before 15 weeks gestation had similar rates to non-smokers!

Does a history of cervical excisional procedures affect risk for pre-term delivery?

Up for depate

What are the maternal characteristics that increase the risk for preterm labor?

- Non-Hispanic black race


- BMI <19


- Low economic status


- Stressful life events

What are the maternal medical history characteristics that increase the risk for preterm labor?

- Previous preterm delivery


- Previous abortions (>1 vs none)


- Uterine anomalies

What are the infection characteristics that increase the risk for preterm labor?

- BV


- Intrauterine infection


- Periodontal infection

What are the pregnancy characteristics that increase the risk for preterm labor?

- Shortened cervix


- Multiple gestation


- Use of assisted reproductive technology


- Interpregnancy interval <6 months


- Cocaine or heroin use


- Alcohol use (>10 drinks/week)


- Tobacco use


- Maternal abdominal surgery during pregnancy


- Maternal depression during pregnancy


- Presence of thyroid auto-antibodies


- Polyhydramnios or oligohydramnios


- Vaginal bleeding from placental abruption or placenta previa


- Low vitamin D level

What can be done to prevent / decrease risk for preterm delivery?

- Antenatal progesterone


- Screening and treatment of BV (best with earlier screening, focus on high risk women, and appropriate choice of antibiotic)


- Cervical cerclage

What is the mechanism by which progesterone prevents preterm labor?

- Reduction of gap junction formation


- Oxytocin antagonism


- Maintenance of cervical integrity


- Anti-inflammation

What medication formulation and dosage is indicated for prior spontaneous preterm delivery?

17 alpha-hydroxyprogesterone caproate


250mg IM weekly from 16 to 36 weeks




(Vaginal progesterone is not recommended)


(Do not discontinue until 36 weeks as it can increase risk of recurrent PTD if stopped)

What medication formulation and dosage is indicated for women with no prior spontaneous preterm delivery but who have a cervical length ≤20mm at ≤24 weeks?

Vaginal progesterone gel 90mg daily until 36 weeks


OR


Vaginal progesterone capsule 200mg daily until 36 weeks

What is the appropriate screening for cervical length anomalies?

In women with a history of preterm delivery (who are also being treated with 17P), evaluate with transvaginal U/S every 2 weeks from 16 to 23-6/7 weeks gestation

If a woman has a hx of cervical length on screening is <25 mm, what is the appropriate treatment?

Cervical cerclage should be offered in addition to vaginal progesterone if <20 mm

In the case of multiple gestation, does progesterone or cerclage improve outcomes in regards to preterm delivery?

No, neither has been shown to improve outcomes

Has the cervical pessary been shown to decrease rates of preterm delivery?

Currently being studied for prevention

Does treatment of periodontal disease affect pregnancy outcomes?

Although it is associated with preterm delivery, treatment does not affect outcome

Does treatment of bacteriuria affect pregnancy outcomes?

Treatment does prevent progression to pyelonephritis and does reduce incidence of low-birth-weight newborns, but does not lower rate of preterm delivery

Does treatment of asymptomatic bacterial vaginosis affect pregnancy outcomes?

- Asymptomatic BV is associated with preterm delivery and late miscarriage


- There is no evidence to show that treatment improves outcomes


- USPSTF recommends against screening in low-risk women and finds insufficient evidence to recommend for or against screening in high risk patients

What are the appropriate treatments for BV in pregnancy?

- Clindamycin cream 2% - one full applicator (5g) intravaginally at bedtime for 7 days


- Clindamycin 300mg PO BID for 7 days


- Clindamycin ovules 100mg intravaginally at bedtime for 3-6 days




(Clindamycin has better outcomes than metronidazole)

Does smoking cessation affect rates of preterm delivery?

Yes, women with a previous preterm delivery who smoked during that pregnancy had a decreased risk of subsequent preterm delivery if they quit smoking

What is the best method for getting pregnant women to quit smoking during pregnancy?

Programs using rewards plus social support

When a woman presents with premature contractions, what are the goals of assessment?

1. Determine if membranes are ruptured


2. Determine if infection is present


3. Stratify risk of preterm delivery

What are the criteria for diagnosis of preterm labor?

- Regular uterine contractions + change in cervical dilation or effacement in a woman at <37 weeks


- OR regular uterine contractions + cervical dilation of at least 2 cm

How do you determine if a woman who presents with premature contractions has ruptured her membranes?

- History


- Leakage of fluid from cervical os during sterile speculum exam


- Nitrazine reaction of fluid


- Ferning of fluid


- Placental alpha micro-globulin-1 test (AmniSure)


- U/S for oligohydramnios


- Amnioinfusion of indigo carmine (if above tests are non-diagnostic)

What do you assess in a woman who presents with premature contractions in regards to the possibility of an infection?

- STI status

- UTI


- Chorioamnionitis, possibly subclinical


How do you determine the likelihood of premature delivery in a woman who presents with premature contractions?

- History


- Fetal fibronectin level (if nothing per vagina for 24 hours)


- Transvaginal cervical length U/S

What kind of physical exam is appropriate for a woman who has possibly ruptured her membranes?

- Sterile speculum exam (direct observation of amniotic fluid leaking from cervical os and pooling in vaginal vault are diagnostic of ruptured membranes - gentle fundal pressure or cough can help facilitate leakage)


- Digital cervical exam should be avoided to minimize risk of infection

What are the microscopic findings associated with the fluid from ruptured membranes?

When air dried on a slide it demonstrates ferrying or arborization

What can cause a false positive ferrying test?

If cervical mucus is inadvertently tested

What is the "nitrazine test"?

Nitrazine paper checks pH:


pH of amniotic fluid is 7.1 - 7.3 (amniotic fluid will change from orange to blue in this case)(normal vaginal environment is 4.5 - 6.0)

What pH is associated with the fluid from ruptured membranes?

pH of amniotic fluid is 7.1 - 7.3 (amniotic fluid will change from orange to blue in this case)




(normal vaginal environment is 4.5 - 6.0)

What can cause a false positive nitrazine test?

Presence of blood, semen, or bacterial vaginosis

If you are unable to determine if a woman's membranes have ruptured based on exam, microscopic exam, and pH testing / nitrazine testing, what can you do for equivocal cases?

AmniSure test - test for placenta alpha microglobulin-1 protein in cervicovaginal fluid (96% sensitive and 99% specific)

If there has been prolonged rupture of membranes and very little fluid is present for analysis, what can be done to determine if membranes have ruptured?

U/S to look for oligohydramnios (not diagnostic, but does support diagnosis)




If still uncertain, U/S guided transabdominal instillation of indigo carmine into amniotic fluid may be used; if blue dyed fluid passes through vagina, stains a pad or tampon, then rupture of membranes is confirmed

What should you have a high index of suspicion for when evaluating women with preterm contractions?

Infection

What infections should be tested for in women with preterm contractions?

- STIs


- UTIs


- BV


- Consider subclinical chorioamnionitis (test for GBS by vaginal / rectal culture unless it has been done in last 5 weeks)

What are the classic findings of chorioamnionitis?

- Fever


- Uterine tenderness


- Foul-smelling discharge


- Maternal tachycardia

What bacteria is associated with chorioamnionitis?

GBS

How should you test for GBS infection?

Vaginal / rectal culture

If delivery appears likely and GBS culture is either unavailable or positive, what should be done?

GBS prophylaxis

What percentage of women presenting to triage with preterm contractions will go on to deliver prematurely?

<15%

What test can aid in identifying women at low risk for preterm delivery who present with symptoms of preterm labor?

Fetal Fibronectin Test (may be done between 24 and 34 weeks)




Should not be used in women with active vaginal bleeding, or when intercourse, digital vaginal exam, or endovaginal U/S has occurred in preceding 24 hours because can yield false positive results

What is Fetal Fibronectin (fFN)?

Extracellular matrix glycoprotein found at maternal-fetal interface




In normal pregnancies, it is almost undetectable in vaginal secretions; when there are disruptions of maternal-fetal interface it gets released into vaginal secretions

What is the utility of the Fetal Fibronectin Test?

- Used to identify women at low risk for delivery in following 10-14 days


- Negative predictive value is >99% for delivery within 14 days


- Positive predictive value is only 13-30% for delivery in 7-10 days for symptomatic patients

What is the utility of cervical length measurement in determine risk for preterm delivery?

- CL >30mm have low risk of delivery within 7 days (regardless of fFN results)


- CL 15-30mm have low risk (<5%) of delivery within 7 days if fFN is negative


- CL <15mm have high risk of delivery within 7 days (27% if negative, 52% if positive)

What are the overall strategies for management of preterm labor?

- Maternal transfer to facility with higher level nursery if indicated


- Administration of corticosteroids


- Antibiotic prophylaxis of neonatal GBS


- Consider magnesium for neuroprotection


- Preparation for preterm birth

What are the benefits of antenatal corticosteroids on fetal outcomes in preterm labor?

Reduces risk of:


- Neonatal mortality


- Respiratory distress syndrome


- Intraventricular hemorrhage


- Necrotizing entercolitis


- Need for respiratory support, intensive care admissions


- Systemic infections in first 48 hours of life

Who should get a course of antenatal corticosteroids?

- Women between 24-34 weeks who are at risk for preterm delivery within 7 days


- Single repeat dose improves outcomes for women <33 weeks who remain at risk of delivery within 7 days, and who received first dose at least 14 days prior


- Further doses do not show additional benefit, and are not recommended

How long are the optimal benefits of antenatal corticosteroids?

Benefits wane after a week

What is the dosing of betamethasone for antenatal dosing?

Two doses of 12mg IM twice administered 24 hours apart

What is the dosing of dexamethasone for antenatal dosing?

Four doses of 6mg IM administered every 6 hours

Is there any difference between betamethasone and dexamethasone in terms of outcomes on preterm delivery?

Dexamethasone shows a decrease in intraventricular hemorrhage and length of NICU stay

Is it worth giving antenatal steroids if you can't get all of the doses in?

Yes, even the first dose shows benefit

Should you accelerate dosing of antenatal corticosteroids when preterm delivery is suspected?

No, there is no evidence of improved outcomes with "accelerated dosing"

Which mediation is given for preterm delivery for neuroprotection?

Magnesium sulfate

What is the appropriate dosing of magnesium sulfate for neuroprotection?

Immediately before and at time of delivery of preterm infant for women between 24 - 34 weeks gestation at high risk of delivery within 24 hours:


- 4g over 20-30 minutes (loading dose) --> 1g/hr continued until birth or for 24 hours (maintenance dosing) --> no immediate repeat doses


OR


- 6g over 20-30 minutes (loading dose) --> 2g/hr continued until birth or for 12 hours (maintenance dosing) --> if <6 hours have elapsed since cessation, restart maintenance dose; if >6 hours have elapsed, rebolus and then start maintenance dose

What are the benefits of magnesium sulfate in preterm delivery?

Decreases rate of cerebral palsy

What is the goal of tocolytic drugs?

Used for short-term pregnancy prolongation (up to 48 hours)




Goal: administer antenatal corticosteroids, magnesium sulfate for neuroprotection, antibiotics for GBS prophylaxis, and maternal transfer if necessary

When should tocolytics be used?

Between viability and 34 weeks estimated gestational age with established preterm labor and the absence of evidence of maternal or fetal compromise?

Under what circumstances would it not be safe to give tocolytics for preterm labor?

Maternal or fetal compromise:


- Chorioamnionitis


- Severe pre-eclampsia


- Maternal instability


- Fetal demise or lethal anomaly


- Worrisome fetal status

After cessation of labor, is there any benefit for long-term tocolysis?

No benefit for further prolongation of pregnancy

What are the types of tocolytic meds?

- Nifedipine


- Betamimetics (terbutaline, ritodrine)


- Indomethacin


- Magnesium sulfate

What are the characteristics of nifedipine for tocolysis?

- Decreases likelihood of delivering within 48 hours


- Compared to betamimetics, it increased time before birth


- Decreased maternal adverse events


- Improved neonatal outcomes (very preterm birth, respiratory distress syndrome, necrotizing enterocolitis, intraventricular hemorrhage, neonatal jaundice, and NICU admissions)


- Compared to magnesium sulfate, it has decreased maternal events and decreased NICU admissions

What are the beta mimetic tocolytic agents?

Terbutaline and Ritodrine

What are the characteristics of beta-mimetics (terbutaline and ritodrine) for tocolysis?

- Effective in delaying delivery for 48 hours (not to be used >48 hours)


- No studies show improvement in fetal outcome


- Maternal adverse effects are significant (potential for maternal cardiac complications and mortality)

What are the characteristics of indomethacin for tocolysis?

- NSAID


- Increases likelihood of delivery at >37 weeks


- Increases gestational age at delivery


- Low maternal adverse effects


- Concern regarding interference with fetal prostaglandin synthesis and fetal safety (conflicting results - mostly no effects, but concern for severe intraventricular hemorrhage, necrotizing enterocolitis, and periventricular leukomalacia)


- May be first-line agent for preterm labor before 32 weeks


- Should not be used for more than 48 hours or beyond 32 weeks gestation (due to concern for premature closure of ductus arteriosus)

What are the characteristics of magnesium sulfate for tocolysis?

- Not been shown to prolong pregnancy or improve neonatal outcomes compared to placebo or other tocolytics


- Possible increased risk of fetal and neonatal mortality


- Possible increased length of NICU admission


- Can be used for neuroprotection


- Should use additional tocolytic for woman who continue to labor when given magnesium sulfate for neuroprotection


- Caution use of calcium channel blockers and magnesium sulfate (theoretical maternal cardiac complications)

What is the leading cause of mortality due to infection among neonates?

GBS

If a woman is admitted for preterm labor, how do you determine the need for a GBS swab?

If she has not had prior testing within the last 5 weeks or results are not available

If you do not have GBS swab results and a woman is entering true labor, what should be done?

Start GBS prophylaxis until delivery

What antibiotics are routinely used for GBS prophylaxis?

Penicillin G (5 million units IV initially, then 2.5-3 million units q4h until delivery)




OR




Ampicillin (2g IV initially, then 1g IV q4h until delivery)

What antibiotics are used for GBS prophylaxis if the woman has a hx of allergy to PCN?

If patient has a history of anaphylaxis, angioedema, respiratory distress, urticaria with PCN or cephalosporins, Clindamycin or Vancomycin




If no severe allergy history, Cefazolin

What is the dose of Cefazolin for GBS prophylaxis?

2g IV initial dose, then 1g IV q8h until delivery

How do you determine whether to give Clindamycin or Vancomycin for GBS prophylaxis?

If severe PCN/cephalosporin allergy:


- Give Clindamycin if isolate is susceptible to clindamycin and erythromycin




- Give Vancomycin if isolate is not susceptible to those

What is the dose of Clindamycin for GBS prophylaxis?

Clindamycin 900mg IV q8h until delivery

What is the dose of Vancomycin for GBS prophylaxis?

Vancomycin 1g IV q12h until delivery

What percentage of preterm deliveries are preceded by PPROM?

25-30%

What causes preterm premature rupture of membranes (PPROM)?

Thought to be the result of infection or inflammation that leads to activation of metalloproteinase activity which breaks down the membranes leading to rupture


(In the context of placental abruption, thrombin may be involved)

What is more likely to cause PROM and Preterm Labor the earlier in pregnancy it happens?

Infection

How soon is delivery likely to happen after rupture of membranes?

Within a week, however the earlier in pregnancy rupture occurs, the greater the potential for a latency period

How common is an intraamniotic infection after preterm premature rupture of membranes? What increases the risk?

13-60%


Increased risk by digital vaginal examination

How should a patient with suspected preterm premature rupture of membranes (PPROM) be initially evaluated?

- Accurate dating


- Sterile speculum exam (avoid digital vaginal exam)


- U/S evaluation


- Assessment of fetal lung maturity


- Screen for infection


- Fetal monitoring (fetal HR and uterine contraction monitoring)

How does oligohydramnios affect the U/S evaluation?

Decreases the accuracy of fetal weight and gestational assessment

How does oligohydramnios affect the fetus?

Increases the likelihood of cord compression and other complications

How do you assess for fetal lung maturity in patients with suspected PPROM?

Vaginal amniotic fluid may be tested for lamellar body count and phosphatidyl glycerol to evaluate fetal lung maturity between 32-34 weeks gestation




Amniocentesis allows collection of fluid for fetal pulmonary maturity testing and for evaluation of testing

What infections should be screened for in patients with suspected PPROM?

- GBS


- STIs

When should labor be induced for women with PPROM?

At 34 weeks

What are the management strategies for patients with PPROM?

- Monitor for clinical infection


- Antepartum fetal testing - non-stress test and biophysical profile


- Antibiotic therapy - ampicillin and erythromycin (or azithromycin)


- Corticosteroids


- Magnesium sulfate (neuroprotection)

What are the signs of clinical infection you should watch for in women with PPROM?

- Maternal fever


- Uterine tenderness


- Fetal tachycardia

What antibiotics are indicated for PPROM for gestations between 24-32 weeks?

Initial Therapy:


- Ampicillin 2g IV q6h for 48 hours (1g q6h is adequate for GBS prophylaxis)


- Erythromycin 250mg IV q6h for 48 hours


- Some substitute Azithromycin 1g PO for Erythromycin




Follow-Up Therapy:


- Amoxicillin 250mg PO q8h x5 days


- Erythromycin base 333mg PO q8h x5 days

What are the benefits of antibiotic therapy in PPROM?

Prolongs pregnancy and decreases fetal morbidity, chorioamnionitis, and maternal infection

What are the benefits of corticosteroids in patients with PPROM?

Reduces risks of:


- Neonatal respiratory distress syndrome


- Intraventricular hemorrhage


- Necrotizing entercolitis


- Trending towards decreased neonatal mortality




No increased incidence of maternal or neonatal infection

Is there a benefit to tocolysis in PPROM?

Lacks evidence of benefit in PPROM

What medication is used for neuroprotection in PPROM?

Magnesium sulfate

How should you manage a patient >34 weeks with PPROM?

Electively deliver


Corticosteroids and antibiotics are no longer indicated

How should you manage a patient 24-34 weeks with PPROM?

- Antibiotics, corticosteroids, magnesium sulfate


- Monitor for infection


- Manage expectantly until 34 weeks if there is no evidence of fetal compromise and labor does not begin spontaneously

What is PROM?

Premature Rupture of Membranes:


- Rupture of membranes before onset of labor in pregnancies beyond 37 weeks

How common is PROM?

8%

What typically happens in women with PROM?

Spontaneous labor occurs quickly, 95% of women managed expectantly will deliver within 28 hours

What are the primary concerns for women with PROM?

Maternal and neonatal infection

What steps can be taken to reduce risk for maternal and neonatal infection in PROM?

Antibiotics and early induction in women who are colonized with GBS

What are the benefits of induction of labor for women with PROM?

Reduction in chorioamnionitis and endometritis (without affecting risk of operative delivery)




No effect on number of neonatal infections, but did decrease number of NICU admissions

What should be done for women with PROM when labor does not follow?

Induction with oxytocin




If mother and fetus are well, expectant management is acceptable along with counseling on potential risk




For women with GBS, they should receive antibiotics and be encouraged to have induction to reduce neonatal GBS infection

How common are preterm deliveries?

1 in 9 pregnancies in US

Where should a premature delivery occur?

In a facility with a high-volume level III NICU --> better neonatal outcomes




If delivery is not imminent and level III services are unavailable, maternal transfer is indicated

Who may benefit from delayed umbilical cord clamping?

Preterm infants (recommended as standard practice)

What are the benefits of delayed umbilical cord clamping in preterm infants?

Reduces incidence of intraventricular hemorrhage and need for neonatal transfusion

What is the procedure for delayed cord clamping?

- Infant should be held at or below level of placenta for 30-120 seconds before clamping the cord


- Neonatal resuscitation efforts should not be delayed to allow for delayed cord clamping however

Is there any preference for vaginal or cesarean delivery for preterm babies?

No, decision should be made based on standard obstetrical indications




Cesarean delivery is higher for preterm than for term because the indications for surgery are more common in prematurity

Why are cesarean deliveries more common in prematurity?

Preterm fetuses are more likely to have a malpresentation and are less able to handle the potential stresses of labor

When is vacuum assisted delivery contraindicated? Why?

For fetuses <34 weeks due to risk of intracranial hemorrhage

What gestational age is the "threshold of viability"?

22-25 weeks

What tool can be used to counsel parents on outcomes for fetuses at the threshold of viability?

National Institute of Child Health and Human Development - tool is based on outcomes of neonates based on gestational age, weight, sex, and administration of antenatal corticosteroids




Should also use outcome data from the facility's NICU to assist with decision making